AJP - Lung Cellular and Molecular Physiology, Vol 273, Issue 5 913-L920, Copyright © 1997 by American Physiological Society
Glycosylation differences between a cystic fibrosis and rescued airway cell line are not CFTR dependent
X. Jiang, W. G. Hill, J. M. Pilewski and O. A. Weisz
Renal-Electrolyte Division Laboratory of Epithelial Cell Biology, University of Pittsburgh, Pennsylvania 15213, USA.
Altered glycosylation of mucus and membrane glycoconjugates could explain
reported differences in binding of bacterial pathogens to cystic fibrosis
(CF) versus normal tissue. However, because bacteria can alter cell surface
glycoconjugates, it is not possible to assess the role of cystic fibrosis
transmembrane conductance regulators (CFTR) in glycosylation in these
studies. To address this issue, we have developed quantitative lectin
binding assays to compare cell surface glycosylation in well-matched
immortalized CF cells and rescued cell lines. The CF airway bronchial
epithelial cell line IB3-1 consistently bound more peanut agglutinin (PNA)
than its clonal derivative S9, which stably expresses functional wild-type
CFTR. Pretreatment with neuraminidase increased PNA binding and abolished
the difference between the two cell lines. However, infection of the IB3-1
cells with a replication-deficient recombinant adenovirus encoding CFTR
restored CFTR function but did not alter PNA binding to cells. In contrast,
treatment with the weak base ammonium chloride increased PNA binding to
both cell lines as expected. Our data show that even clonally related CF
and rescued cells can exhibit significant differences in carbohydrate
processing. Although the differences that we found are consistent with the
proposed role for CFTR in modulating intraorganellar pH, our data strongly
suggest that they are CFTR independent. These studies add a cautionary note
to the interpretation of differences in glycosylation between CF and normal
primary tissues and immortalized cells.
